<!DOCTYPE html>

<html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Title</title>

        <style type="text/css">
            .wrapper { margin: 15px auto ; border: 1px solid blue ; font-size: 0 ; }
            .first , .second , .third { background: #FFFF00 ;  font-size: 14px; }
            .second { display: inline-block ; background: #1e9fff ; }
            .third { display: flex ; }
        </style>
    </head>
    <body>

        <div class="wrapper">
            <div class="first">hello</div>
        </div>

        <div class="wrapper">
            <span class="second">world</span>
            <span class="second">world</span>
            <span class="second">world</span>
        </div>

        <div class="wrapper">
            <p class="third">new</p>
            <p class="third">new</p>
            <p class="third">new</p>
            <p class="third">new</p>
        </div>

    </body>
</html>